1. Field of the Invention
This invention relates to a method for the production of a silicon-on-insulator (SOI) substrate which is so configured as to have a single crystal silicon layer superposed in the form of a semiconductor single crystal layer on an insulator substrate.
2. Description of the Prior Art
The semiconductor element manufactured with a SOI substrate permits a decrease in the parasitic capacitance of wiring and, therefore, readily allows an increase in the speed of operation and further enjoys easy isolation of elements and precludes the phenomenon of latch-up which would occur in the case of a CMOS. By this reason, the SOI substrates have been recently attracting attention as wafers fit for the manufacture of three-dimensional devices which are capable of diversifying functions, augmenting the operational speed, and exalting the integration.
Heretofore, for the production of the SOI construction by the bonding of wafers, there has been employed the method which comprises directly applying a single crystal silicon wafer 101 having a SiO.sub.2 film 101a formed on one surface thereof (hereinafter referred to as "wafer") as illustrated in FIG. 10 fast to a wafer 102 having no SiO.sub.2 film formed thereon, to make adhered, subsequently heat-treating the adhered wafers, thereby bonding them, and then grinding and polishing the wafer 101 of the bonded wafers thereby converting the wafer 101 into a thin film and consequently giving rise to a SOI substrate 103 as illustrated in FIG. 11.
The method described above is at a disadvantage in entailing difficulty in producing inexpensively the SOI substrate because it requires either of the bonded wafers to be ground and polished until it is decreased to a residual layer thickness in the range of 1 to some tens of .mu.m and consequently suffers from waste of not less than about 90% of the wafer.